package cn.xinzhi.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.Reader;

public class MyBatisUtil {
    /**
     * 工具类
     */
        private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
        private static SqlSessionFactory sqlSessionFactory;
        /**
         * 加载位于src/mybatis-config.xml配置文件
         */
        static{
            try {
                Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
            } catch (IOException e) {
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }
        /**
         * 禁止外界通过new方法创建
         private MyBatisUtil(){}
         /**
         * 获取SqlSession
         */
        public static SqlSession getSqlSession(){
            //从当前线程中获取SqlSession对象
            SqlSession sqlSession = threadLocal.get();
            //如果SqlSession对象为空
            if(sqlSession == null){
                //在SqlSessionFactory非空的情况下，获取SqlSession对象
                sqlSession = sqlSessionFactory.openSession();
                //将SqlSession对象与当前线程绑定在一起
                threadLocal.set(sqlSession);
            }
            //返回SqlSession对象
            return sqlSession;
        }
        /**
         * 关闭SqlSession与当前线程分开
         */
        public static void closeSqlSession(){
            //从当前线程中获取SqlSession对象
            SqlSession sqlSession = threadLocal.get();
            //如果SqlSession对象非空
            if(sqlSession != null){
                //关闭SqlSession对象
                sqlSession.close();
                //分开当前线程与SqlSession对象的关系，目的是让GC尽早回收
                threadLocal.remove();
            }
        }

}
